In Vitro Anthelminthic Efficacy of Hypoestes forskaolii (Vahl) R.Br (Acanthaceae) Extracts on Gastrointestinal Nematodes of Sheep

The anthelminthic efficacy of the crude extracts of Hypoestes forskaolii (Vahl) R.Br (Acanthaceae) against gastrointestinal nematodes (GIN) in sheep was investigated using the in vitro egg hatch inhibition assay. Faecal samples were collected from sheep with naturally occurring infection of GIN (Trichostrongylus spp., Chabertia ovina, Cooperia spp., Haemonchus contortus and Teladorsagia spp.). Crude leaf extracts of H. forskaolii was obtained using increasing polarity solvents: n-hexane, chloroform, chloroform:methanol 9:1, methanol. Thiabendazole (0.2 µg/mL and 0.5 µg/mL) was used as a positive control and untreated GIN eggs in deionised water served as the negative control. All the extracts exhibited a weak ovicidal activity against GIN (less than 50% of egg hatch). Noteworthy, the n-hexane extract showed a percentage of inhibition of egg hatching greater than other extracts inhibiting the 30.8% at the concentration of 1 mg/mL showing a dose-dependent effect on nematode eggs hatching. Further studies are needed to investigate the effects of extracts used and to evaluate the ovicidal effects of other extracts of H. forskaolii.